Angle trisector



D. E. HANSON ANGLE TRISECTOR Nov. 14, 1961 Filed Dec.

\f/AN GLE BISECTOR INVENTOR.

DONALD E. HANSON United States Patent Filed Dec. 3, 1956, Ser. No.625,891 1 Claim. (Cl. 33-1) The present invention relates generally toinstruments and more particularly to an instrument capable of trisectingany angle.

The primary object of this invention is to provide an instrument capableof accurately trisecting any angle, which instrument eliminates allmathematical computations necessary in the conventional procedure foraccomplishing this function, whereby the possibility of error and timeand elfort normally required for tn'secting an angle would be greatlyreduced.

Finally, it is an object to provide an instrument of the aforementionedcharacter which is simple, safe and convenient to operate, and whichwill give generally eflicient and durable service.

With these objects definitely in view, along with other objects whichwill become evident as this description proceeds, this inventionconsists in the novel construction, combination and arrangement ofelements and portions, as will be hereinafter fully described in thespecific-ation, particularly pointed out in the claim, and illustratedin the drawing which forms a material part of this disclosure, and inwhich:

FIGURE 1 is the plan or top view of the instrument, the view beingproposed as illustrating how the instrument is used;

FIGURE 2 is a side elevation of the instrument;

FIGURE 3 is a transverse sectional view of the portion of the instrumentadjacent the sighting bore;

FIGURE 4 is a fragmentary sectional view of the pivot peg and adjacentparts; and

FIGURE 5 is a fragmentary sectional view of the pivot peg with thelockscrew.

Similar characters of reference indicate similar or iden tical elementsand portions throughout the specification and throughout the views ofthe drawing.

Referring now to the drawing and to FIGURE 1 in particular my instrumentincludes the base arm 12 on one end of which is mounted a short cylinder13 which provides the sighting bore 14. In the sighting bore 14,preferably adjacent what may be considered the bottom end thereof, thereis mounted a transparent disc 15 with cross hairs 16 painted thereon orotherwise applied thereto. At the outer end of the base arm 12 there isprovided a pivot peg 18 which is mounted for free rotary movement aboutits vertical axis by means of a large headed screw 17. In the end of thebase arm 12 adjacent to the pivot peg 18, there is provided a sightingor register notch 20, said notch being aligned with sighting cross hairs16 and the axis of the pivot peg 18. The cross hairs 16 are centered inthe sighting bore 14, in order to accurately position the instrument foruse.

The secondary arm 22 is mounted on the cylinder 13 and a second pivotpeg 24 wtih a hand knob 26 on its upper end is pivotally mounted in theouter end portion of the said secondary arm. It is important to notethat the axes of the pivot peg 18 and second pivot peg 24 are equallydistant from the point of intersection of the sighting cross hairs 16. Areference notch 28 in the outer end of the secondary arm 22 is alignedwith the sighting cross hairs 16 and the axis of the pivot peg 24. Thepivot peg 18 and pivot peg 24 are identical in size and design exceptthat pivot peg 24 is drilled and tapped to accommodate lockscrew 26.

The traverse bar 30 is of approximately three times the length of thebase arm 12 and is recti-cylindrical with a is on the bisector line.

'ice

'2 pointer 32 Qnthe and adjacent t t e p o P 4- This Painter 32 m y be uitary with the bar 30, con it a dcWn-turnedterminal or a le g h s a t ly eq to the height of the traverse bar above the {bottom surface of thebase leg 12. The traverse bar 30 is rigidly fixed to the pivot peg 24 bya set screw 34 or otherwise.

The portion 36 of the traverse bar 30, between the axis of the pivot peg24 and the extremity of the pointer 32 has an effective or horizontallength equal to the distance fi'orn the center defined on the'crosshairs 16 to the axis of either one of the pivot pegs 18 or 24which are equidistant from the cross hairs.

As illustrated, the arm 22 is pivoted on the cylinder 13 above thecorresponding portion of the arm 12 and the arm 22 has the outer endportion 38 thereof offset downwardly to the level of the arm 12. In thisway the instrument is adapted to lie flat on the surface whereon it isused.

The angle to be trisected is first bisected in the conventional manner,the bisector line being extended from the point of intersection of theangle sufiiciently to either side of the point of intersection toaccommodate the instrument, as indicated in FIGURE 1. The instrument isthen placed on the angle with the sighting cross hairs 16 coincidingwith the point of intersection of the angle and the register notch 20 onthe base leg 12 centered on one leg of the angle. The base arm 12 isheld in this position and the hand knob 26 moved until the pointer 32The entire instrument is now held in this position while a referencemark is made, indicating the location of the reference notch 28 in thesecondary arm 22. The instrument is then removed and a trisector line 40is drawn through the reference mark and the point of intersection of theangle, said line being extended beyond the point of intersection as at42 in order to trisect the desired angle. If required, a secondtrisector line can be obtained by using the instrument with the registernotch 20 aligned with the remaining leg 44 of the original angle.

Minor variation from the form disclosed herein may be resorted towithout departure from the spirit and scope of this invention, and thesaid specification and drawing should be considered as illustrativerather than limiting.

I claim: Apparatus for trisecting an angle having an apex formed by twointersecting lines, and an angle-bisecting line, said apparatuscomprising:

a single base arm having an indicating notch at one end thereof, saidindicating notch being on the longitudinal axis of said base arm;

a single secondary arm having an indicating notch at one end thereof,said indicating notch being on the longitudinal axis of said secondaryarm;

means for pivotally connecting together the other ends of said base armand said secondary arm for relative pivotal movement about a first axis;

means, comprising a sighting bore having a reticule positioned abovesaid first axis for positioning said first axis above the apex of saidangle, whereby said reticule and first axis may be positioned above theapex of said angle, and said indicating notch of said base arm may bepositioned in alignment with one said line of said angle to cause saidbase arm to line up along said line of said angle; a rigid traverse bar;

means for slidably and pivotably mounting said bar at a point of saidbase arm to pivot about a second References Cited in thefile 0t thispatent UNITED STATES'PATENIS Steed Sept. 1, 1914 Galvin Aug. 2, 1927Tihenko Nov. 7, 1933 Thibodeau Mar. 7, 1950 Hart et a1. June 16, 1953FOREIGN PATENTS Germany Dec. 19', 1892 France Nov. 5, 1956 OTHERREFERENCES Page 34' of the Triseetion Problem, a book by Robert C.Yates, 1 942. (Copy in Div. 66.)

